Deformation switch assembly



April 1957 R. cs. HELSPER 2,790,872

DEFORMATION SWITCH ASSEMBLY Filed Dec 2 53 INVENTQR Hold-l ATTd EYUnited States Patent DEFORMATION SWITCH ASSEMBLY Robert G. Helsper,South Orange, N. J., assignor to Specialties Development Corporation,Belleville, N. J., a corporation of New Jersey Application December 2,1953, Serial No. 395,683

7 Claims. (Cl. 200-86) The present invention relates to electricalcircuit makers, and, more particularly, to a deformable switch assemblywhich is operable by being compressed at any point along its length.

Specifically, the present invention aims to improve the switch assemblydisclosed in copending application for United States Letters Patent,Serial No. 353,781, filed May 8, 1953, assigned to my assignee, issuedon even date herewith.

The switch assembly disclosed in the aforementioned applicationgenerally comprises first, second and third elongate, superimposed,flexible, electrically conductive strips; a series of lengthwise spacedpad-like insulating elements extending diagonally between the first andsecond strips to hold these strips out of contact with each other; asecond series of similar elements between the second and third strips,the elements of the first and second series being staggered with respectto each other; and a tubular, deformable, nonconductive housing for thestrips.

This assembly is made by adhesively securing the padlike elements to oneor more of the strips in their proper position and then inserting thestrips in the housing. It will be appreciated that this mode ofarranging the pad-like elements, it performed by hand, is tedious,cumbersome and expensive due to the labor cost involved, and, ifperformed by automatic machinery, requires fairly complicated and costlyequipment.

Accordingly, an object of the present invention is to provide a switchassembly, having all the beneficial structural features of theaforementioned switch assembly, which is constructed and arranged in apractical and highly economical manner.

Another object is to provide such a switch assembly which comprises aminimum number of simple and relatively inexpensive parts.

A further object is to provide such a switch assembly, the deformablecharacteristic of which can be varied without changing the dimensions ofthe parts thereof.

Other and further objects of the invention will be obvious upon anunderstanding of the illustrative embodiment about to be described, orwill be indicated in the appended claims, and various advantages notreferred to herein will occur to one skilled in the art upon employmentof the invention in practice.

In accordance with the present invention, the foregoing objects areaccomplished by providing a switch assembly which comprises first andsecond elongate, superimposed, flexible, electrically conductive strips;a third strip of the foregoing description having thereon a spiralwinding of a nonconductive ribbon formed with spaced apart convolutionsand being sandwiched between the first and second strips; and a tubular,deformable nonconductive housing for the strips.

A preferred embodiment of the invention has been chosen for purposes ofillustration and description, and is shown in the accompanying drawing,forming a part of the specification, wherein:

2,790,872 Patented Apr. 30, 1957 Fig. 1 is a fragmentary sideelevational view, partly in section, illustrating a switch assembly, inaccordance with the invention, connected in an alarm circuit.

Fig. 2 is a fragmentary perspective view of the strips and the ribbonwinding on the middle strip apart from the housing.

Fig. 3 is an enlarged sectional view taken along the line 3-3 on Fig. 1.

Referring to drawing in detail, there is shown a switch assemblygenerally comprising three superimposed metallic strips 10, 11 and 12, aspiral winding of a nonconductive ribbon 14 about the middle strip 11which is sandwiched between the strips 10 and 12, and a tubulardeformable nonconductive housing 15 for the strips.

The strips 10, 11 and 12 may be of equal width or the middle strip 11may be of a lesser width, as shown, so that, when the ribbon Winding 14is applied thereon, the effective width thereof is about equal to orslightly greater than the width of the strips 10 and 12. The strips areformed of a highly conductive, springy material such as Phosphor bronzeand are of a desirable width and thickness. For example, the strips 10and 12 may have a width of about five-sixteenths of an inch and thestrip 11 may have a width of about one-quarter of an inch, and all ofthe strips have a thickness of about ten thousandths of an inch.

The ribbon, tape or band 14 may be fiat or oval, and may be formed ofrubber or rubber-like or other yieldable material having insulatingproperties. For example, an excellent material for this purpose issilicone rubber because it has these desired properties and can bereadily handled and wound or twisted about the strip 11 either by handor simple automatic machinery. The width and thickness of the ribbon mayvary, but, for example, the width may be about one-fourth of an inch andthe thickness thereof may be about one-sixteenth of an inch.

As shown herein, the ribbon is spirally wound on the strip 11 in zig-zagfashion with adjacent convolutions at the same fiat side surface of thestrip spaced apart a distance slightly greater than the width of theribbon. For example, the convolutions of the ribbon extend diagonallyacross the side surfaces at an angle of about 45 with respect to thelongitudinal axis of the strips, whereby, if the strip 11 is about twiceas wide as the ribbon, the space between convolutions will be abouttwice the width of the ribbon. The angle at which the convolutionsextend across the strip may be varied to vary the space between adjacentconvolutions, and thereby vary the degree of force required to bringadjacent strips into contact. This is a very desirable feature becausethe characteristics of the strip assembly can be altered as desiredwhile still using the same materials in the manufacture of the switchassembly and without changing the dimensions of the materials.

As shown in Fig. 3, the housing comprises a flat base strip 16, and acover strip 17 having a channel section 18 for receiving the stripassembly and having side flanges 19 secured upon the base strip 16. Thechannel section may be dimensioned to snugly receive the strip assemblyincluding the strips 10 and 12 and the middle strip 11 with the winding14 thereon, but having a width slightly greater than the strips 10 and12 to provide a loose fit at the side edges of these strips, wherebythese strips are free to move towards the strip 11 when pressure isapplied thereon.

The housing strips 16 and 17 are formed of rubber or rubber-likeinsulating material which is readily deformed, provides a watertightseal, and is weather resistant at temperatures between about 65 F. andabout F.

The switch assembly is adapted to be used in an alarm circuit, includinga source of energy 20 and alarm means herein shown as a bell 21. In thiscircuit, the strips greases 10 and 12 are electrically connected to eachother at one 01' both ends thereof and to one terminal of the bell, thestrip 11 is connected to one side of the source, and the other terminalof the bell is connected to the other side of the'source, so that, uponestablishing contact between the strip 11 and the strip 10 and/or thestrip 12, the circuit is closed and an alarm is given.

From the foregoing description, it will be seen that the presentinvention provides a practical and reliable switch assembly which isextremely economical to manufacture and assemble.

As various changes may be made in the form, construction and arrangementof the parts herein, without departing from the spirit and scope of theinvention and without sacrificing any of its advantages, it is to beunderstood that all matter herein is to be interpreted as illustrativeand not in any limiting sense.

I claim:

1. A deformation switch assembly comprising first and secondsuperimposed, flexible, electrically conductive, thin, metallic, flatstrips of relatively narrow width and of indefinite, continuous length;a third strip of the fore going description having thereon a spiralwinding of a resilient, electrically nonconductive ribbon formed withspaced apart convolutions and being sandwiched between said first andsecond strips such that said first and third, and said second and thirdstrips are normally held out of contact with each other by theconvolutions of said ribbon; and an enclosed tubular, deformable,electrically nonconductive housing of indefinite, continuous length forconfining the side edges of said strips and said spiral winding, saidhousing comprising a channel member and a flat base member sealed tosaid channel member to provide weather-tight protection for said strips.

2. A switch assembly according to claim 1, wherein said strips are widerthan said ribbon.

3. A switch assembly according to claim 1, wherein said convolutionsextend diagonally across the flat sides of said strip.

4. A switch assembly according to claim 2, wherein said convolutions aredisposed at an angle of about 4-5 with respect to the longitudinal axisof said third strip.

5. A switch assembly according to claim 1, wherein the distance betweenadjacent convolutions along the longitudinal axis of said third strip isgreater than the width of said ribbon.

6. A switch assembly according to claim 1, wherein said ribbon is formedof silicone rubber.

7. A switch assembly according to claim 1, wherein the width of saidthird strip is less than that of said first and second strips by abouttwice the thickness of said ribbon.

References Cited in the file of this patent UNITED STATES PATENTS2,132,685 Hampton et al -2 Oct. ll, 1938 2,163,960 Paver June 27, 19392,611,049 Roby .a Sept. 16, 1952 FOREIGN PATENTS 272,893 Great Britaina- Aug. 30, 1928

